This application claim priority under 35 USC xc2xa7119 of application number 77602/2000, filed Dec. 18, 2000 in the Republic of Korea.
The present invention relates to a catalyst for polymerization of olefin and a method of polymerization using the same. More particularly the present invention relates to a new catalyst for polymerization of olefin of a hybrid concept and the method of polymerization using the same, which includes synthesizing a titanium compound chelated by means of amide and cyclopentadiene-based ligands, and then activating the same by means of conventional MgCl2, etc., instead of using expensive methylaluminoxane.
The polymerization reaction of olefin, in which a transition metal compound reacts with olefin, there have been continuous efforts to enhance the characteristics of polymers produced therein by changing the reaction environments of the transition metal compounds. In particular, there have been significant advances in the efforts to control the reaction environments where a transition metal compound reacts with olefin, by using a metallocene compound in which the ligand of a transition metal has been changed into a cyclopentadiene ligand. Into the 1980""s, the homogeneous catalyst system using a metallocene compound started to receive spotlight on account of its (co)polymerization of xcex1-olefin resulting in superior characteristics in terms of impact strength, transparency, etc. In particular, by synthesizing a metallocene compound having particular substituents, such as an indenyl, cycloheptadiene, or fluorenyl group, which control the electrical or stereo-spatial environment of the catalytic metal, a metallocene catalyst was developed to control the stereoregularity and molecular weights of polymers. The application of such catalyst systems has been expanding in the recent years. Moreover, by creating a heterogenious catalyst system by supporting a metallocene compound on an inorganic carrier, there have been advances into the development of a catalyst. For example it is reported that such catalysts can control the particle morphology of polymers while producing a superior set of co-polymers. For example, U.S. Pat. Nos. 5,439,995, 5,455,316, etc. report the production of a non-homogeneous catalyst system, having superior particle morphology and co-polymerization characteristics. This result is reportedly achieved by supporting zirconocene and titanocene compounds onto a magnesium or silica support. The use of a supported metallocene catalyst is disadvantageous in that it requires a complicated organometal-chemical synthesis to generate the catalyst and uses expensive methylaluminoxane (hereinafter MAO) or a boron compound as a co-catalyst during the polymerization of olefin. As such, there remains a continuous demand for a compounds, which are easier to synthesize. Moreover, the polymers produced by a metallocene catalyst have narrow distribution of molecular weights (Mw/Mn=2xcx9c3) and thus exhibit unfavorable attributes in terms of polymer processing.
In recent years, chelated compounds, either bidentate or tridentate, have been used as catalyst components, i.e., transition metals such as non-metallocene catalysts, beyond-metallocene catalysts, or organometallic catalysts. In using such chelated compounds, there has been much effort to develop a catalyst producing narrow distribution of molecular weights, but which is not as difficult to synthesize as the above noted metallocene compounds. Japanese Laid-Open Patent Sho 63-191811 presents results of polymerization of ethylene and propylene, carried out by means of a substituted compound as a catalyst component. As disclosed therein, a halide ligand of a titanium halide compound was substituted with a TBP (6-tert-butyl-4-methylphenoxy) ligand. As a result of polymerization of ethylene and propylene by using methylaluminoxane (MAO) as a co-catalyst, it is reported that the formation of polymers of high activities and molecular weights (average molecular weight=3,600,000 or more). U.S. Pat. No. 5,134,104 describes a catalyst for polymerization of olefin, having a dioctylamine titanium halide compound ((C8H17)2NTiCl3) as a catalyst component, in which the halide ligand of TiCl4 is changed into an amine ligand having a large steric volume. J. Am. Chem. Soc. (117, p. 3008) discloses a catalyst for polymerization of olefin using a compound in which a 1,1xe2x80x2-bi-2,2xe2x80x2-naphthol ligand is chelated to a titanium or zirconium transition metal, or the derivatives thereof, wherein said chelated compound can limit the steric space of the transition metal. Moreover, Japanese Laid-Open Patent Pyung 6-340711 and EP 0606125A2 disclose chelated catalysts for polymerization of olefin of narrow distribution of molecular weights while producing polymers of high molecular weights. The reported results are achieved by means of substituting halide ligand of titanium and zirconium transition metal compounds with a phenoxy group.
In the recent years, much attention has been paid to a non-metallocene catalysts for polymerization of olefin, which use an amine-based chelated transition metal compound. For example see Organometallics, 15, p.2672 (1996), and Chem. Commun., p.2623 (1996). Such literature papers include examples of utilizing catalysts for polymerization of olefin by synthesizing titanium compounds chelated with various forms of diamide compounds. J. Am. Chem. Soc., 120, p.8640 (1998), introduces polymerization reaction of propylene using titanium and zirconium compounds chelated by diamide. Organometallics, 17, p.4795 (1998), reports a catalyst for polymerization using titanium or zirconium chelated by ((Aryl-NCH2CH2)2O) and ((Aryl-NCH2CH2)2S). Organometallics, 17, p.4541 (1998), discusses a catalyst for polymerization of olefin by using titanium, vanadium, and chromium compounds, which are chelated by N,N-diphenyl-2,4-pentanediimine ligands. Moreover, J. Am. Chem. Soc., 118, p.10008 (1996), describes a catalyst for polymerization of olefin, which is a titanium compound chelated by (Aryl-NCH2CH2CH2N-Aryl). U.S. Pat. No. 5,502,128 suggests a method of sPS polymerization of olefin using titanium zirconium compounds chelated by amidinate ligands. Organmetallics, 18, p.2046 (1999), introduces a non-metallocene catalyst of high activity by using a titanium or zirconium compound chelated by a phosphinimide-based amide compound. The aforementioned non-metallocene catalysts for polymerization of olefin using chelated titanium or zirconium compounds were developed as homogeneous catalyst systems using expensive MAO or boron compound as a co-catalyst. They were not intended as a heterogeneous catalyst system, which can be activated by a inorganic carrier. As such, it is difficult to directly apply such a system to the processes requiring catalysts having superior particle morphology, the processes which entail most of the conventional polymerization processes (e.g., gas phase polymerization process). thus there remain an unmet need for the development of a catalyst, which can be easily activated by an inorganic carrier (such as MgCl2, which is utilized by most of the conventional processes) while having a non-metallocene compound or metallocene compound as a catalyst component.
The present invention provides solutions to the problems of prior art as above. As a catalyst component, the present invention uses a titanium compound chelated by an amide-base ligand and a cyclopentadiene-based ligand, which can be applied to the conventional process by the unique method of synthesis thereof. In this regard, one aspect of the present invention lies in providing a method of polymerization of olefin, which produces polymers of narrow distribution of molecular weights and even distribution of composition of co-polymers by using a catalyst for polymerization of olefin of a new concept, which can be activated by an inorganic carrier such as magnesium halide.